Code to download a file on Buttton click

Some times we have need like when user click on a button then we want to perform some server side operation and then a automatic download file prompt should be shown to user to download a file..
below code will help you in above situation:
write it at server side on any event.

create below class or place functions in same page but its recommended to take separate class for it
class DownloadLibrary
{
public static string getContentType(string Fileext)
{
string contenttype = "";
switch (Fileext)
{
case ".xls":
contenttype = "application/vnd.ms-excel";
break;
case ".doc":
contenttype = "application/msword";
break;
case ".ppt":
contenttype = "application/vnd.ms-powerpoint";
break;
case ".pdf":
contenttype = "application/pdf";
break;
case ".jpg":
case ".jpeg":
contenttype = "image/jpeg";
break;
case ".gif":
contenttype = "image/gif";
break;
case ".ico":
contenttype = "image/vnd.microsoft.icon";
break;
case ".zip":
contenttype = "application/zip";
break;
default: contenttype = "";
break;
}
return contenttype;
}

public static void downloadFile(System.Web.UI.Page pg, string filepath)
{
pg.Response.AppendHeader("content-disposition", "attachment; filename=" + new FileInfo(filepath).Name);
pg.Response.ContentType = clsGeneral.getContentType(new FileInfo(filepath).Extension);
pg.Response.WriteFile(filepath);
pg.Response.End();
}
}


now write below code in ur aspx page
DownloadLibrary.downloadFile(this.Page,filepath);